Science advise needed

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Science advise needed

Postby Tania » Tue Jan 25, 2011 12:53 pm

Hi! My kid is doing some experiment.. how needs to be added to a solution (eg. water) to check whether it contains sulphur dioxide/sulphur?

Any science guru who can help??

Thanks.

Tania
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Postby James Ang » Tue Jan 25, 2011 2:30 pm

Googles, copy and paste, based on my understanding of your query..

Sulfur Dioxide

1)  Has no colour.

2)  Has a choking smell.

3)  Will turn moist blue litmus paper red,
or moist universal indicator paper red - it is acidic.

4)  Will put out a lit splint.



Specific test.

Sulfur dioxide will turn acidified
potassium dichromate(VI) solution from orange to green.
Chromium is reduced from (VI) to (III).
Last edited by James Ang on Tue Jan 25, 2011 2:36 pm, edited 1 time in total.

James Ang
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Postby James Ang » Tue Jan 25, 2011 2:33 pm

The Barium Chloride Test for Sulfate (SO42-) Ions.
Any soluble sulfate will give a white precipitate of barium sulfate.

barium chloride + zinc sulfate zinc chloride + barium sulfate.
BaCl2(aq)      +      ZnSO4(aq)                   ZnCl2(aq)     +     BaSO4(s)

The ionic equation is    Ba2+(aq)  +  SO42-(aq)    BaSO4(s)

The test is made in the presence of dilute hydrochloric acid
to remove any carbonate or sulfite ions which may be present.
These ions will also produce a precipitate which would confuse the results.

James Ang
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Postby Tania » Wed Jan 26, 2011 8:15 am

Thanks James!

Where can i buy the litmus paper?? Will tap water turn the litmus paper blue/red?

So the present of sulphur in the solution will turn the moist blue litmus paper red? Can you please confirm?

Thanks!

Tania
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